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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
+<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" />
+<!--
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ This file is generated from xml source: DO NOT EDIT
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+ -->
+<title>mod_brotli - Apache HTTP Server Version 2.4</title>
+<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
+<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
+<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
+<script src="../style/scripts/prettify.min.js" type="text/javascript">
+</script>
+
+<link href="../images/favicon.ico" rel="shortcut icon" /></head>
+<body>
+<div id="page-header">
+<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
+<p class="apache">Apache HTTP Server Version 2.4</p>
+<img alt="" src="../images/feather.png" /></div>
+<div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="../images/left.gif" /></a></div>
+<div id="path">
+<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.4</a> &gt; <a href="./">Modules</a></div>
+<div id="page-content">
+<div id="preamble"><h1>Apache Module mod_brotli</h1>
+<div class="toplang">
+<p><span>Available Languages: </span><a href="../en/mod/mod_brotli.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="../fr/mod/mod_brotli.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a></p>
+</div>
+<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Compress content via Brotli before it is delivered to the
+client</td></tr>
+<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
+<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>brotli_module</td></tr>
+<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_brotli.c</td></tr>
+<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.4.26 and later.</td></tr></table>
+<h3>Summary</h3>
+
+ <p>The <code class="module"><a href="../mod/mod_brotli.html">mod_brotli</a></code> module provides
+ the <code>BROTLI_COMPRESS</code> output filter that allows output from
+ your server to be compressed using the brotli compression format before being sent to the client over
+ the network. This module uses the Brotli library found at
+ <a href="https://github.com/google/brotli">https://github.com/google/brotli</a>.</p>
+</div>
+<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><h3>Topics</h3>
+<ul id="topics">
+<li><img alt="" src="../images/down.gif" /> <a href="#recommended">Sample Configurations</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#enable">Enabling Compression</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#proxies">Dealing with proxy servers</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#precompressed">Serving pre-compressed
+content</a></li>
+</ul><h3 class="directives">Directives</h3>
+<ul id="toc">
+<li><img alt="" src="../images/down.gif" /> <a href="#brotlialteretag">BrotliAlterETag</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#brotlicompressionmaxinputblock">BrotliCompressionMaxInputBlock</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#brotlicompressionquality">BrotliCompressionQuality</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#brotlicompressionwindow">BrotliCompressionWindow</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#brotlifilternote">BrotliFilterNote</a></li>
+</ul>
+<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&amp;list_id=144532&amp;product=Apache%20httpd-2&amp;query_format=specific&amp;order=changeddate%20DESC%2Cpriority%2Cbug_severity&amp;component=mod_brotli">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&amp;component=mod_brotli">Report a bug</a></li></ul><h3>See also</h3>
+<ul class="seealso">
+<li><a href="../filter.html">Filters</a></li>
+<li><a href="#comments_section">Comments</a></li></ul></div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="recommended" id="recommended">Sample Configurations</a></h2>
+ <div class="warning"><h3>Compression and TLS</h3>
+ <p>Some web applications are vulnerable to an information disclosure
+ attack when a TLS connection carries compressed data. For more
+ information, review the details of the "BREACH" family of attacks.</p>
+ </div>
+ <p>This is a simple configuration that compresses common text-based content types.</p>
+
+ <div class="example"><h3>Compress only a few types</h3><pre class="prettyprint lang-config">AddOutputFilterByType BROTLI_COMPRESS text/html text/plain text/xml text/css text/javascript application/javascript</pre>
+</div>
+
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="enable" id="enable">Enabling Compression</a></h2>
+ <div class="warning"><h3>Compression and TLS</h3>
+ <p>Some web applications are vulnerable to an information disclosure
+ attack when a TLS connection carries compressed data. For more
+ information, review the details of the "BREACH" family of attacks.</p>
+ </div>
+
+ <h3><a name="output" id="output">Output Compression</a></h3>
+ <p>Compression is implemented by the <code>BROTLI_COMPRESS</code>
+ <a href="../filter.html">filter</a>. The following directive
+ will enable compression for documents in the container where it
+ is placed:</p>
+
+ <pre class="prettyprint lang-config">SetOutputFilter BROTLI_COMPRESS
+SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png)$ no-brotli</pre>
+
+
+ <p>If you want to restrict the compression to particular MIME types
+ in general, you may use the <code class="directive"><a href="../mod/mod_filter.html#addoutputfilterbytype">AddOutputFilterByType</a></code> directive. Here is an example of
+ enabling compression only for the html files of the Apache
+ documentation:</p>
+
+ <pre class="prettyprint lang-config">&lt;Directory "/your-server-root/manual"&gt;
+ AddOutputFilterByType BROTLI_COMPRESS text/html
+&lt;/Directory&gt;</pre>
+
+
+ <div class="note"><h3>Note</h3>
+ The <code>BROTLI_COMPRESS</code> filter is always inserted after RESOURCE
+ filters like PHP or SSI. It never touches internal subrequests.
+ </div>
+ <div class="note"><h3>Note</h3>
+ There is an environment variable <code>no-brotli</code>,
+ set via <code class="directive"><a href="../mod/mod_env.html#setenv">SetEnv</a></code>, which
+ will disable brotli compression for a particular request, even if
+ it is supported by the client.
+ </div>
+
+
+
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="proxies" id="proxies">Dealing with proxy servers</a></h2>
+
+ <p>The <code class="module"><a href="../mod/mod_brotli.html">mod_brotli</a></code> module sends a <code>Vary:
+ Accept-Encoding</code> HTTP response header to alert proxies that
+ a cached response should be sent only to clients that send the
+ appropriate <code>Accept-Encoding</code> request header. This
+ prevents compressed content from being sent to a client that will
+ not understand it.</p>
+
+ <p>If you use some special exclusions dependent
+ on, for example, the <code>User-Agent</code> header, you must
+ manually configure an addition to the <code>Vary</code> header
+ to alert proxies of the additional restrictions. For example,
+ in a typical configuration where the addition of the <code>BROTLI_COMPRESS</code>
+ filter depends on the <code>User-Agent</code>, you should add:</p>
+
+ <pre class="prettyprint lang-config">Header append Vary User-Agent</pre>
+
+
+ <p>If your decision about compression depends on other information
+ than request headers (<em>e.g.</em> HTTP version), you have to set the
+ <code>Vary</code> header to the value <code>*</code>. This prevents
+ compliant proxies from caching entirely.</p>
+
+ <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">Header set Vary *</pre>
+</div>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="precompressed" id="precompressed">Serving pre-compressed
+content</a></h2>
+
+ <p>Since <code class="module"><a href="../mod/mod_brotli.html">mod_brotli</a></code> re-compresses content each
+ time a request is made, some performance benefit can be derived by
+ pre-compressing the content and telling mod_brotli to serve them
+ without re-compressing them. This may be accomplished using a
+ configuration like the following:</p>
+
+ <pre class="prettyprint lang-config">&lt;IfModule mod_headers.c&gt;
+ # Serve brotli compressed CSS files if they exist
+ # and the client accepts brotli.
+ RewriteCond "%{HTTP:Accept-encoding}" "br"
+ RewriteCond "%{REQUEST_FILENAME}\.br" "-s"
+ RewriteRule "^(.*)\.css" "$1\.css\.br" [QSA]
+
+ # Serve brotli compressed JS files if they exist
+ # and the client accepts brotli.
+ RewriteCond "%{HTTP:Accept-encoding}" "br"
+ RewriteCond "%{REQUEST_FILENAME}\.br" "-s"
+ RewriteRule "^(.*)\.js" "$1\.js\.br" [QSA]
+
+
+ # Serve correct content types, and prevent double compression.
+ RewriteRule "\.css\.br$" "-" [T=text/css,E=no-brotli:1]
+ RewriteRule "\.js\.br$" "-" [T=text/javascript,E=no-brotli:1]
+
+
+ &lt;FilesMatch "(\.js\.br|\.css\.br)$"&gt;
+ # Serve correct encoding type.
+ Header append Content-Encoding br
+
+ # Force proxies to cache brotli &amp;
+ # non-brotli css/js files separately.
+ Header append Vary Accept-Encoding
+ &lt;/FilesMatch&gt;
+&lt;/IfModule&gt;</pre>
+
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="BrotliAlterETag" id="BrotliAlterETag">BrotliAlterETag</a> <a name="brotlialteretag" id="brotlialteretag">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>How the outgoing ETag header should be modified during compression</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BrotliAlterETag AddSuffix|NoChange|Remove</code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>BrotliAlterETag AddSuffix</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_brotli</td></tr>
+</table>
+ <p>The <code class="directive">BrotliAlterETag</code> directive specifies
+ how the ETag hader should be altered when a response is compressed.</p>
+ <dl>
+ <dt>AddSuffix</dt>
+ <dd><p>Append the compression method onto the end of the ETag, causing
+ compressed and uncompressed representations to have unique ETags.
+ In another dynamic compression module, mod_deflate, this has been
+ the default since 2.4.0. This setting prevents serving "HTTP Not
+ Modified" (304) responses to conditional requests for compressed
+ content.</p></dd>
+ <dt>NoChange</dt>
+ <dd><p>Don't change the ETag on a compressed response. In another dynamic
+ compression module, mod_deflate, this has been the default prior to
+ 2.4.0. This setting does not satisfy the HTTP/1.1 property that all
+ representations of the same resource have unique ETags. </p></dd>
+ <dt>Remove</dt>
+ <dd><p>Remove the ETag header from compressed responses. This prevents
+ some conditional requests from being possible, but avoids the
+ shortcomings of the preceding options. </p></dd>
+ </dl>
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="BrotliCompressionMaxInputBlock" id="BrotliCompressionMaxInputBlock">BrotliCompressionMaxInputBlock</a> <a name="brotlicompressionmaxinputblock" id="brotlicompressionmaxinputblock">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum input block size</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BrotliCompressionMaxInputBlock <var>value</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>(automatic)</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_brotli</td></tr>
+</table>
+ <p>The <code class="directive">BrotliCompressionMaxInputBlock</code> directive specifies
+ the maximum input block size between 16 and 24, with the caveat that
+ larger block sizes require more memory.</p>
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="BrotliCompressionQuality" id="BrotliCompressionQuality">BrotliCompressionQuality</a> <a name="brotlicompressionquality" id="brotlicompressionquality">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Compression quality</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BrotliCompressionQuality <var>value</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>BrotliCompressionQuality 5</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_brotli</td></tr>
+</table>
+ <p>The <code class="directive">BrotliCompressionQuality</code> directive specifies
+ the compression quality (a value between 0 and 11). Higher quality values
+ result in better, but also slower compression.
+ </p>
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="BrotliCompressionWindow" id="BrotliCompressionWindow">BrotliCompressionWindow</a> <a name="brotlicompressionwindow" id="brotlicompressionwindow">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Brotli sliding compression window size</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BrotliCompressionWindow <var>value</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>BrotliCompressionWindow 18</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_brotli</td></tr>
+</table>
+ <p>The <code class="directive">BrotliCompressionWindow</code> directive specifies the
+ brotli sliding compression window size (a value between 10 and 24). Larger
+ window sizes can improve compression quality, but require more memory.</p>
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="BrotliFilterNote" id="BrotliFilterNote">BrotliFilterNote</a> <a name="brotlifilternote" id="brotlifilternote">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Places the compression ratio in a note for logging</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BrotliFilterNote [<var>type</var>] <var>notename</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_brotli</td></tr>
+</table>
+ <p>The <code class="directive">BrotliFilterNote</code> directive
+ specifies that a note about compression ratios should be attached
+ to the request. The name of the note is the value specified for
+ the directive. You can use that note for statistical purposes by
+ adding the value to your <a href="../logs.html#accesslog">access log</a>.</p>
+
+ <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">BrotliFilterNote ratio
+
+LogFormat '"%r" %b (%{ratio}n) "%{User-agent}i"' brotli
+CustomLog "logs/brotli_log" brotli</pre>
+</div>
+
+ <p>If you want to extract more accurate values from your logs, you
+ can use the <var>type</var> argument to specify the type of data
+ left as a note for logging. <var>type</var> can be one of:</p>
+
+ <dl>
+ <dt><code>Input</code></dt>
+ <dd>Store the byte count of the filter's input stream in the note.</dd>
+
+ <dt><code>Output</code></dt>
+ <dd>Store the byte count of the filter's output stream in the note.</dd>
+
+ <dt><code>Ratio</code></dt>
+ <dd>Store the compression ratio (<code>output/input * 100</code>)
+ in the note. This is the default, if the <var>type</var> argument
+ is omitted.</dd>
+ </dl>
+
+ <p>Thus you may log it this way:</p>
+
+ <div class="example"><h3>Accurate Logging</h3><pre class="prettyprint lang-config">BrotliFilterNote Input instream
+BrotliFilterNote Output outstream
+BrotliFilterNote Ratio ratio
+
+LogFormat '"%r" %{outstream}n/%{instream}n (%{ratio}n%%)' brotli
+CustomLog "logs/brotli_log" brotli</pre>
+</div>
+
+<h3>See also</h3>
+<ul>
+<li><code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code></li>
+</ul>
+</div>
+</div>
+<div class="bottomlang">
+<p><span>Available Languages: </span><a href="../en/mod/mod_brotli.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="../fr/mod/mod_brotli.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a></p>
+</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&amp;A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
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